Storage summary chart

Histogram type chart of daily summary info.

A daily summary is produced from the same data file plotted in the wellhead pressure chart. The last 14 days of this summary are plotted. Text values are available on the web page.

Values in this file are:
1. Date as month/day
2. All day average gallons in storage, as inferred from averaging pressure values while not pumping.
3. Average gallons in storage between midnight and 1am. "First hr"
4. Average gallons in storage between 1am and midnight. "Last hr"
5. Time in minutes that pump was running.
6. "Pumped" is calculated gallons assuming 5.0 gpm.
7. "Gain" is difference between early and late storage levels.
8. "Usage" is "pumped" minus "gain". Any overflow shows up as usage.
9. "Timer" is estimate of how many minutes to pump each event tomorrow (within limit of 110) to bring level to 9500 gallons.
10. "Air" is an index of rapid variations in pressure, used to detect air drawn into the submersible pump.
11. "Data" is the percent of expected data that was received.


Pressure chart

Sensing the pressure at the well only gives good reading of tank level when water in the pipe is not moving. When water is moving, flow resistance in the pipe causes pressure drop that adds to or subtracts from the static head of water at the storage tank. With water going up (pump running) pressure reads high, initially by 10 psi but becoming less as flow decreases due to the pump being exposed to higher load as water level in the well is pumped down. With water coming down the pipe (drinkers filling) pressure reads low by some amount.

Problem is you know the pipe length involved in the pump flow, but different drinkers are at various distances from the tanks so the loss will vary with drinker as well as flow rate. This would make it hard to quantify the flow rate to the drinkers.

The more cattle drink down the level the more the drinker valves open. As soon as they quit drinking the float valves start reducing the flow so, with less pressure drop, the resulting reading at the well goes up, slowing as the drinkers fill. Pressure drop is proportional to length and to square of flow rate. (constant pipe size assumed) The confusing pressure drops are expected to be minimal between 11pm and 1am and this is when the daily tank levels are estimated.

To sum up: remember that the level inferred from the right-hand gallon scale is only accurate when there is no flow in the line between well and tanks.